[tex4ht] Why tex4ht changes apostrophe to Right Single Quotation Mark?

[Nasser M. Abbasi]

On 1/9/2018 3:09 AM, Michal Hoftich wrote:
> Hi Nasser,
> 
>>> What do I need to do to keep apostrophe as apostrophe
>>> in the HTML?
> 
> this is the default LaTeX behavior, you will get the quotation mark
> even in PDF. You may try to use the `upquote` package, which will fix
> this issue in verbatim.
> 
> Best regards,
> Michal
> 

Houston, we have a problem:

upquote works. It fixes '  in verbatim. _but_ when adding
the --lua option, it no longer works. something breaks.

Here is a MWE

------------------
\documentclass[11pt]{article}
\usepackage{upquote}
\begin{document}

\begin{verbatim}
`set` and 'set'
\end{verbatim}

\end{document}
--------------------

Compiled with make4ht -u foo.tex  ===> OK
Compiled with make4ht --lua -u foo.tex ==> not OK
Compiled with make4ht --lua foo.tex ==> not OK

Not ok, means it does not fix the ' but the ` is fixed
in all cases.

Why is adding --lua (compiling with lualatex) makes
upquote package not work in tex4ht? This only affect tex4ht.

lualatex foo.tex  ===> OK

Using texlive 2017 on Linux.

Thanks
--Nasser